for "Can-Do Charles"
What I was relaying was not that the carb cleaner was the major correction , but that the leaky rubber gasket around air cleaner bowl was allowing dust particles in and the dust particles were "mucking" up my idle control unit. 87 300E has not repeated the irregular idle speed trouble in the 2 years since I did that repair.
Something else I did could have fixed it even tho I did not realize; possible inadvertently fixing a small vac leak when I removed the idle canister's connections, or something like that.
I always look for the simplest answers first. Don't assume major expensive parts have gone bad without first taking the time to study mechanical and obvious issues.
Luck to you,